The use of intravascular catheters, guidewires and other types of elongate delivery members for accessing and treating various types of vascular disease is well-known. In general, a suitable intravascular catheter, guidewire, or other delivery member inserted into the vascular system, e.g., via introduction through a femoral or jugular artery or vein, and navigated through the vasculature to a desired target site. By using an appropriately sized device having the requisite performance characteristics, such as “pushability” “steerability”, “torquability” and most important, distal tip flexibility, virtually any target site in the vascular system may be accessed, including within the tortuous cerebral vasculature.
For example, a stent for example, may be loaded in a reduced diameter configuration onto (or into) a catheter or other type of delivery wire, and then introduced into the lumen of a body vessel. Once delivered to a target location within the body vessel, the stent may then be expanded (or allowed to expand) to an enlarged configuration within the vessel to support and reinforce the vessel wall, while maintaining the vessel in an open, unobstructed condition. The stent may be configured to be self-expanding, expanded by an internal radial force such as a balloon, or a combination of self-expanding and balloon expandable.
By way of another example, balloon catheters are used in a number of endovascular applications, including for temporarily or permanently occluding blood flow either distal or proximal of a treatment site during neurological examinations, delivering diagnostic agents such as contrast media, assisting in neurovascular embolic coiling of an aneurysm or arteriovenous malformation (AVM), and dilating narrowed blood vessels caused by vasospasm. During therapeutic procedures such as the ones mentioned above, fast aspiration-mediated deflation of the balloon catheter is desired in order to quickly restore sufficient or normal blood flow to the brain in order to avoid potential neurological impairment. To facilitate rapid deflation, a single lumen balloon catheter may be provided with an internal axial support shaft made from a slotted, or otherwise perforated, tubular member, such as a metallic hypotube. Such slotted hypotubes provide superior performance characteristics (i.e., pushability, steerability, torquability, and flexibility) for accessing cerebral blood vessels. Exemplary slotted hypotubes manufactured for this purpose are disclosed and described in U.S. Pat. No. 8,585,643 and U.S. Patent Application Publication No. 2013/0184644, the entire disclosures of which are incorporated herein by reference, as though set forth in full. In particular, openings in the tubular support shaft underlying the balloon may function as inflation/deflation ports. However, openings in the tubular support shaft that are not enclosed by the balloon must be sealed (e.g., coated) to prevent egress of balloon inflation fluid delivered through the support shaft lumen. Such tubular support shafts may also be used, inter alia, as components of guidewires. When used as components of guidewires, the slotted hypotubes are preferably substantially sealed or prevent fluids from entering into the inner lumen of the tube, and also to enhance lubricity.
Methods of coating slotted support member hypotubes are described in U.S. Pat. No. 7,989,042, the entire disclosure of which is incorporated herein by reference, as though set forth in full. Such methods can either result in a substantially continuous coating, i.e., with most slots coated, or an at least partially discontinuous coating, i.e., with most slots open. However, the presence of coating materials within the slots reduces the flexibility and other performance characteristics of the hypotubes due to the stiffening caused by the coating material. This problem is exacerbated because the slotted hypotubes are often incorporated at the distal end portions of the respective catheters, guidewires and other delivery members, where having a high degree of flexibility is most crucial.
Accordingly, there is an ongoing need for providing adequately fluid sealed, slotted tubular support components for use in catheters, guidewires and other elongate delivery members used to access target sites in the vasculature, without compromising their performance characteristics.